But the truth goes deeper, and darker. There’s also egoism, sadism, spitefulness, and more. And behind this rogues gallery of all our worst inclinations on the surface, a central, common core of human darkness lies, according to new research.

In a new study, psychologists from Germany and Denmark have mapped this driving force behind all our darkest impulses, and given it a name. Meet D, the newly identified Dark Factor of Personality.

The theoretical framework of the D factor has its underpinnings in what’s known as the g factor: a construct proposed by English psychologist Charles Spearman over a century ago, when he observed that individuals who performed well on one kind of cognitive test were more likely to score well on other kinds of intelligence tests too.

In other words, a ‘general intelligence factor’ could be measured. But it turns out that’s not all scientists are able to detect.

“In the same way, the dark aspects of human personality also have a common denominator, which means that – similar to intelligence – one can say that they are all an expression of the same dispositional tendency,” explains psychologist Ingo Zettler from the University of Copenhagen in Denmark.

In a series of four separate studies involving over 2,500 participants, Zettler and fellow researchers surveyed participants with questions designed to measure their levels of nine distinct dark personality traits: egoism, Machiavellianism, moral disengagement, narcissism, psychological entitlement, psychopathy, sadism, self-interest, and spitefulness.

To do so, participants were asked to disagree with a range of variable ‘dark’ statements, such as: “I know that I am special because everyone keeps telling me so”, “I’ll say anything to get what I want”, “It is hard to get ahead without cutting corners here and there”, and “Hurting people would be exciting”.

With all the responses in hand, they ran a statistical analysis, with the results suggesting that while these dark traits are all distinct, they all overlap to some extent, owing to the central core darkness factor, D, which reveals itself in different ways in different people.

“In a given person, the D factor can mostly manifest itself as narcissism, psychopathy or one of the other dark traits, or a combination of these,” Zettler says.

“But with our mapping of the common denominator of the various dark personality traits, one can simply ascertain that the person has a high D factor. This is because the D factor indicates how likely a person is to engage in behaviour associated with one or more of these dark traits.”

It’s pretty provocative stuff, but you don’t just have to take the researchers’ word for it: you can take the D test yourself.

The team has set up an online portal where you can measure your own D score via a questionnaire.

Why would people want to know? Well, apart from personal curiosity about how dark you really are, the researchers say their findings could one day lead to new discoveries in psychology and therapy, advancing our understanding in how we interpret people’s malevolent actions.

“We see it, for example, in cases of extreme violence, or rule-breaking, lying, and deception in the corporate or public sectors,” Zettler says.

“Here, knowledge about a person’s D-factor may be a useful tool, for example to assess the likelihood that the person will reoffend or engage in more harmful behaviour.”